The present invention is directed to testing, and more particularly to testing a plurality of biofluid drop ejectors arranged to print biological assays.
Many scientific tests such as those directed to biology, genetics, pharmacology and medicine, employ sequences or arrays of biofluid drops upon which the tests are to be performed. In some testing applications up to several thousand biofluid drops are deposited onto a single substrate where a single substrate contains a variety of unique biofluids. For example, in current biological testing for genetic defects and other biochemical aberrations, thousands of the individual biofluids may be placed on a glass substrate at different locations. Thereafter, additional biofluids may be deposited on the same locations to obtain an interaction. This printed biological assay is then scanned with a laser in order to observe changes in a physical property.
In these situations it is critical that the drop ejection devices not be a source of contamination or permit cross-contamination between biofluids. A consideration in this regard is that the biofluid drop ejectors are operating properly. Such proper operation includes that the ejectors are filled, and are ejecting drops in a complete and acceptable form. It is undesirable for the ejectors to be emitting non-fully formed drops.
Existing mechanisms used to produce biological assays fall short in their ability to accurately place the biofluid drops such as to avoid contamination and cross-contamination.
Methods and configurations for testing operation of drop ejection units in a multi-ejector system are provided to determine whether the drop ejectors have been properly filled and/or the ejectors are emitting fully formed droplets. The methods include testing the ejectors prior to drop ejection. In this method, a priming system is used wherein fluid received by the priming system is ejected onto a test substrate to allow a scanner to determine the existence of the fluids at selected locations. The selected locations are correlated to the drop ejection units to determine which ejection units do not have biofluid or sufficient biofluid. Another method tests ejection prior to printing, on a test substrate wherein testing for both the fullness of the ejector units with biofluid as well as proper operation of ejectors is tested. The ejectors, after being primed, eject biofluid drops which are then scanned and correlated to each individual ejector. A further method provided is a laser scattering method wherein a laser beam is interposed between the drop emission path of the ejectors. Laser detection then determines whether a correlated drop ejector is properly emitting droplets.